The po plugin needs to be updated to match the urlto sub API and
signature changes. Else a wiki with the po plugin enabled cannot be
refreshed / rebuilt because of (correct) Perl errors.

My po branch contains a fix.
--[[intrigeri]]

> The commit looks sane to me, for what it's worth. Joey, please
> consider merging? --[[smcv]]

>> Merged. --[[Joey]] 

Also, I fear the lack of any useful `$from` parameter might break some
l10n'd link niceness when using `po_link_to = current` but I have not
investigated this yet.
--[[intrigeri]]

> If `urlto` is called without a second parameter, it means we need
> a URL valid from either the CGI URL or any page in the wiki,
> (so we'd previously have set the third parameter true), but we
> don't *necessarily* need an absolute URL - so return what you'd
> have returned if asked for an absolute URL, but looking like
> `/bugs/` rather than `http://ikiwiki.info/bugs/` if possible.
>
> It looks as though `beautify_urlpath` under `po_link_to = current`,
> and 3-argument `urlto`, aren't tested by `t/po.t` - perhaps you
> could add some test cases there? To test 3-argument `urlto` you'd
> need to add `$config{baseurl} = "http://example.com"` or
> something. --[[smcv]]

>> I'm leaving this bug report open until this can be checked. --[[Joey]] 

>>> My `ready/urlto` branch improves the test coverage. The bugfix from
>>> that branch fixes most of `po` too, but leaves behind some perhaps
>>> less-than-ideal behaviour: links where the current language is unknown,
>>> with `po_link_to = current`, always go to the master language,
>>> whereas perhaps it'd be better to go to the negotiated language in
>>> this case? --[[smcv]]